title: PKB/SGK-dependent GSK3-phosphorylation in the regulation of LPS-induced Ca2+ increase in mouse dendritic cells.
abstract: The function of dendritic cells (DCs) is modified by glycogen synthase kinase GSK3 and GSK3 inhibitors have been shown to protect against inflammatory disease. Regulators of GSK3 include the phosphoinositide 3 kinase (PI3K) pathway leading to activation of protein kinase B (PKB/Akt) and serum and glucocorticoid inducible kinase (SGK) isoforms, which in turn phosphorylate and thus inhibit GSK3. The present study explored, whether PKB/SGK-dependent inhibition of GSK3 contributes to the regulation of cytosolic Ca(2+) concentration following stimulation with bacterial lipopolysaccharides (LPS). To this end DCs from mutant mice, in which PKB/SGK-dependent GSK3α,β regulation was disrupted by replacement of the serine residues in the respective SGK/PKB-phosphorylation consensus sequence by alanine (gsk3(KI)), were compared to DCs from respective wild type mice (gsk3(WT)). According to Western blotting, GSK3 phosphorylation was indeed absent in gsk3(KI) DCs. According to flow cytometry, expression of antigen-presenting molecule major histocompatibility complex II (MHCII) and costimulatory molecule CD86, was similar in unstimulated and LPS (1μg/ml, 24h)-stimulated gsk3(WT) and gsk3(KI) DCs. Moreover, production of cytokines IL-6, IL-10, IL-12 and TNFα was not significantly different in gsk3(KI) and gsk3(WT) DCs. In gsk3(WT) DCs, stimulation with LPS (1μg/ml) within 10min led to transient phosphorylation of GSK3. According to Fura2 fluorescence, LPS (1μg/ml) increased cytosolic Ca(2+) concentration, an effect significantly more pronounced in gsk3(KI) DCs than in gsk3(WT) DCs. Conversely, GSK3 inhibitor SB216763 (3-[2,4-Dichlorophenyl]-4-[1-methyl-1H-indol-3-yl]-1H-pyrrole-2,5-dione, 10μM, 30min) significantly blunted the increase of cytosolic Ca(2+) concentration following LPS exposure. In conclusion, PKB/SGK-dependent GSK3α,β activity participates in the regulation of Ca(2+) signaling in dendritic cells.
authors.affiliation: Department of Physiology, University of Tübingen, Gmelinstr. 5, Germany.
authors.forename: Antonella
authors.initials: A
authors.lastname: Russo
authors.forename: Evi
authors.initials: E
authors.lastname: Schmid
authors.forename: Meerim K
authors.initials: MK
authors.lastname: Nurbaeva
authors.forename: Wenting
authors.initials: W
authors.lastname: Yang
authors.forename: Jing
authors.initials: J
authors.lastname: Yan
authors.forename: Madhuri
authors.initials: M
authors.lastname: Bhandaru
authors.forename: Caterina
authors.initials: C
authors.lastname: Faggio
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Shumilina
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
mesh_terms: D000818:Animals; D020013:Calcium Signaling / Q000502:physiology*; D003713:Dendritic Cells / Q000378:metabolism*; D055879:Gene Knock-In Techniques; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D017874:Immediate-Early Proteins / Q000502:physiology*; D008070:Lipopolysaccharides / Q000502:physiology*; D051379:Mice; D008817:Mice, Mutant Strains; D051058:Oncogene Protein v-akt / Q000378:metabolism; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology; D000099184:Serum-Glucocorticoid Regulated Kinases
chemical_list: D038362:Glycogen Synthase Kinase 3; D000071679:Glycogen Synthase Kinase 3 beta; D017874:Immediate-Early Proteins; D008070:Lipopolysaccharides; D051058:Oncogene Protein v-akt; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D000099184:Serum-Glucocorticoid Regulated Kinases; C448021:glycogen synthase kinase 3 alpha
keywords: Ca(2+); Lipopolysaccharide; PI3 kinase; PKB/Akt; SB216763; SGK